SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12db77f7ad271282fd97fe32d15967b0ccde769ab87a3c1135d0bdfbdf3ccea9' 
  AND token = 'XTxtePkl51f8Pg89Yjsfllzc1ayUpefaIatMm03qOso=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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