SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3841d3f721001bccc1b0c04ec983c416ccc03d5c186e76d8e87f581f44689df1' 
  AND token = 'LQRnEiCACfd/+cy4Ju/ZRsZbOCzGwaNMUEJ4YaMSSAM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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