SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4823cdd1a8b20b7beb412aa5becbcc4613a4c5a690117f1f13652b7fffafc981' 
  AND token = '8JZ/WWfp51xGrxKSvMZvqqm41R/RMLg+aWVItZvzFo8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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