SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd3fdea8ebf922870c52ec21579e57585d500f2bb2f639dd7aea80eb2558f05f' 
  AND token = 'y3csSG8ggamq72qvof08GOZLqM4FiVE0ryAZoAYo0xM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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