SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6e4562e51d9c4cb2409aa3a894515af64cc34e41b2b417df7423033b7287b12' 
  AND token = 'pzgkOSbWtcZn1hWjNJw+Bn3PbGIF4th3Rk/UUwrwYJc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}