SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '79f5f21a75c32253378efc9d671948c45fb4d710979bf0af3821f08a852cccba' 
  AND token = '2KFrhFPXcCzVWo91llphNOo/v6Pm5lqOqKSlbnWkUkU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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