SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '84134aeaa9eb23564b8bacd6e20f6416d56a553b3fe60e97a647a56da54b9512' 
  AND token = 'x2yNvgpPkJxXnBPYVJ3jBAW7wXybBlMn7Ludw05ru/U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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