SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '838c234e614923a5da82ef25f6651a96b26d71e740d7396db3cbe72c992cda4a' 
  AND token = 'GKUBGFpiaXe+yKAS/iUj68Rl0v//+hwswsJPStZqdqw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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