SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '714396ea66872503d6acab81dc5ec832b16f7dc8bf7332c3aa53faf9477f6c49' 
  AND token = 'cfBX1XBx1g/9Ta6hLvLv5JVOImQ3PqN6XD4dgKCX8+4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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