SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'bf8574c973a8e5576f87d55804e1f7b5403d05619a1f2928bf4212adf4ce5816' 
  AND token = 'jY+SQl+tuQAwKkSLKYEUUwSOTkQ0GUeyV7e7OlK2Dp4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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