SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '338523027d3d8310011b2312daeef0f6cb585a835af82511eecc6cf63a361c3b' 
  AND token = 'bBlU/5FVAwvczHEfVp50yH1cgHw5J863UVZSuT8nKV4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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