SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76a49b00e03385c0aed1a41efcb14a70f47171db0cef6eca4c116f79dd38212f' 
  AND token = 'rKNrO408QPe9xJ8xj35ongiHztoE1oLELr8/NSZqNGA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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