SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e1f105397b14269c51eb7efa37916e61e9b09d82eb3af5c75a31b296e5d357b' 
  AND token = 'GdLG9IzKIcqrFpVUEFOEhR++zNvs3nO6awCu5ijcu7E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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