SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12698ca3741026adf0b563647813d09999239de8f411434b47295eb7befeae40' 
  AND token = 'QH3sZpso2CAExG3z7VhTCjBCPwY/AbGefrLpraHRV18=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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