SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15ddf2386329b66d0081bfc9d5ddef74d7b3b51a79859aceadc7b5d2d648c0b2' 
  AND token = 'zQKLqDswMeDgv7+lY1sosJ8VgkaJM3GSz+DfyOZLe4M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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