SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1593d7432a8075a57a75f3bbade6fd7a079a65c482983169897db044fd949561' 
  AND token = 'bWai+sVMBkwrvXx1/RIlsgSAaebSjLjbRNf+lXG/GjY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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