SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '068dadefb0d1834b806104f9f851697064eb31d1214c8a88b232e78eb54b13f1' 
  AND token = '2+v8tVJoto/sRPRFlJYEzAX8x8rlktxTD+BdAeRWunE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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