SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd658368b516a42ca64c669e67dd8d4da607e32aeba60235f7ac5ba735de7f3b' 
  AND token = 'GpnyJxnecQzy1/PFC9aLwRwrvT9xISFcLwmrNhtJgB0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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