SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '14549d61ea74f39df14f9d7d86db003b5945e564a394e82f57ef2effbdaf4d94' 
  AND token = 'z88hELnekIOqkHf7Y87fIy8V/UctJmwTeRVP76enOAI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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