SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'da0bb90181eb175c55299a66635a10a0cc004b8684191a4588ff0c3fe8d2d069' 
  AND token = '5RcEIAmHdzcj9Hg5cHtoQooY5TzIQltg3wCAkfpjLSM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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