SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f9ddc43085d4035f013003bf97a4c984ddf0566afb8f2685b00e44131de92296' 
  AND token = 'hFkFaWR37EwmWuOv0sV/Em/Y21gmF9rk8depFBTUHdU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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