SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b3138394e51d89897a171afd0bdb674dd178e64e13b6586de50a475d9faf847' 
  AND token = 'ELhxSHNvL8xYKrvZ6sfDYgGUuu02AXZOd41Zlypl4vA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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