SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '8c9758b0834cb631272f2ff5b9ca9e73f1da79fa66d49f678c52949b1dc65e1f' 
  AND token = '6JpOo4yOaLxBJMipOhul8rseE2X2n+v+FebA1upV/uo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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