SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15c1da168a45e818fd86d84f8029a19edeafacc14f9660598aa0ea9f442efec1' 
  AND token = '1hQD3DNeSLeirD5PmkSD4nwd279/wquvYcIz40Xtyhw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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