SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b88ec1eb6c4cd78ed7c104364237450bfa0807b480b854a7fdb1b075e8a2e651' 
  AND token = 'sFqW2N+UEaWgg9tu5ry0IZrWms0cBCL8qLi+I42clBY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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