SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2821ac83e92f87346ac5fb2ca1401ea0d6add0c4919b18b30b19d9201b618e7f' 
  AND token = 'YpCMTCW2WumY5L4MKD1WuJ2D4/SdaIQB8xzek6NL+34=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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