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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b90b8da35ad4683d6ef9ec6c83b79e34ad6fa402e1a3f952d680e90878ab5fac' 
  AND token = '4SNHRkqrcPo4BkPAiwQXHEt93nJR9+zEMmCeC/xWQ2c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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