SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e656c15db098f75962a7c2dda3b7c7fa69251e8ae2a1cb28d455dadf0c0d2cb2' 
  AND token = 'OeVRaLt9IKfgjnOaUv3uRsnAFzzw0xUKfj6+pN9VTlk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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