SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '847a9e0f948c93fefbcaf50aae0d263d6c73514862b2d3e7e21b1fa53346be4b' 
  AND token = 'yRcCHrXdbiSkpH5m9k6kI1eKCFGyzFnBbcpZgTGvdmk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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