SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6db89695017b98b04a123f698a093fd1f7aa6478bb2d14bf920c657b9ccc9cc8' 
  AND token = 'K9oB55Hpj4oeCCb66fHVZDsTqgke+OsNneIv0tNu5rk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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