SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7b94fcab93823556c5968e9bac222fe31311c3f821ca5a640ff01cb5539acb6' 
  AND token = 'kKKF9jh1/E1aKn+iw6c5CFUyXub+Z0XSmEQ/hLGXoOM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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