SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd0cbef5a0652935a62aaadaf0334d2018d63b1f3983487257d6841f375131738' 
  AND token = 'DSG/TAEgTfEvlVYqMWrqKubBY9Tw7x9VS2gy2DXrRAc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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