SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8d6d333699c04b46a6a983d87f45c6e4d3abcae243bb8fc51e8a8423ba32927' 
  AND token = 'BcPhjpZApqwUKUYaoEzFApJCWhsrrm9DWNoIsTci2gc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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