SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a64d2c079c53fdd7010c948f6bf6d0fb43e7178cb21e855624ecd0d18161c6ae' 
  AND token = 'OE7Zh90Z0ZdU6MgKSlAfVN0MrNEQBgpbr5sJbiJ3P80=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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