SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '394424025554373e7a646da2afcf23f8f508a445a90f057ae707ccca07510dec' 
  AND token = '3sh4qzvleyCMzppc3EEhAJXVvuEWzDHd2Frty2/xASE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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