SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb49c015376fbf4de2493b0e65aed1768a5cc97ba48d8528199210fde5fbb89b' 
  AND token = 'tSVhokZ1nSbehHSVxHT5/Zz7gG50Gsudurs0NrtPQUo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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