SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91fab3333a66a5eb6963bcfc4954767fa5e6b79dd384854a2eca4ff5b8c2bd6b' 
  AND token = 'UAI3WhAJRhHlVWcAyYJkh5QutlXeu0KfCgwQFZEjVjQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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