SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f42f27efab370c8b9f6d85f10562d6dfdc79f96c58e83997bf36fadffcd795ac' 
  AND token = 'ay090MYqsppg8xEcYhIiat11QDy52pmPEGhtuV5dO7w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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