SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fa1f4639e99145453d04497d0638e215f79a17ce7ce0eb55f137bc407f49c120' 
  AND token = 'U6QxCzcRA9mm+mdj6MtLtv7zg39TufuVoMKDI0EXskQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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