SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '321f9e2ebc9ac1646842fb26bed985a0782c3769661d760106c2373780f027be' 
  AND token = 'xyD68iisZAJX3GUc1qxjOfwkt5eP/aAqamEe2ANSWPI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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