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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4948f31ccf3673cbd388baf38eaa9003d13d5a15595830e53b3ab1f1473915e' 
  AND token = 'fQPDbRMVwbkCKXjaph4siw+TjkOhsE3EF1Nx5ZrnP5A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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