SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e43de2e197b3b440d396c6993d86fc2fef94600df17f3f917576f0c9da1d136' 
  AND token = 'wqnUHwUIg3rDphoThWEVgHOmCq1qH9ei1wDkMT9oh3Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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