SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a1633c5a821f401994526581d5835d7bd9b2bc1cbce9c1ccebd9b9a33da64df3' 
  AND token = 'Kko1v6oMkDrBkkMwJUYp79RWBE5BrnqUhLImCQTS/Bg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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