SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8ac349b7205ff43f16b4d998853b1d0d82df8fc5cfd8740c0bb9e38c99f2a768' 
  AND token = 'GGzuXUJZPAQXj/iHhQD40uwlemJMwGByoA5/kfECygE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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