SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6fd896060db1640f697b9040721e69716b7400546989177cfc9286fe95fea31d' 
  AND token = 'IK1yxTy2MzIoxnVd6HKhVs17czkNySQ9aeWtELi5PKo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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