SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4f0c35b3b24f8360f9c0e9c637b425b1fd50848b9d87de176358fe752adc5ff7' 
  AND token = 'zF8+8zgKuFSRc09CzguXkA6ZrhXYDMmZtOiZCVx1FLg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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