SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '88e57294bd7674100a80f08432620071049a94346c41e3479a2a2b91045ff255' 
  AND token = '6W8IH5xoFwS3HgdD2EJ438iBQUS3MBcBDJm44sYdYyo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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