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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8df1aedf084d243d8d08d81c32e253b99032f61d6b84f81d58d44bec1b03d17' 
  AND token = 'j8ODsA7VRMUqpEVPnZcNaT6ShPIhIzrEKOzwJbuJ2Oc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}