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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b28e9278f0fb287225ce09610fa8d5f5b27da05d41a08bfee464dc2e1feccad' 
  AND token = 'PCo2telPdsLC6zWNrgReQamzle4gMHCyrh6syeC4vCU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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