SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '31a1218544e5d13420e61b57667dfbd394ac1ca09d6a4e7ee28235e89e7cd851' 
  AND token = 'wnMF2NDL0GAP/AO+Fj9AaWPWVZEDMJXWaFYHMzGtdXQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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