SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '23f388ef3d4fd9a4a668639544780e79dac5a4382380d7b02b642ca16c557f66' 
  AND token = 'pibMukDWRdDG2keE6tqAZgP88uCDoOa9ZmVr610FNkg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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