SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6bb3499ab4bc01322591cdb9b4b7197fd88f78bc07085c871efc37488f8e76d1' 
  AND token = 'KKwHvBnIdVW/jTsdrfQIS/oHi7dTU+9l2Hi2NLV8ZpQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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