SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'ecd69673b7964849293f5f43df1f5d769803ec80865978b47c5a0bfd1d5b1fb3' 
  AND token = 'E/w4gZTKGA9YFPZObVw/gY6UimwpwkN5xV1opz4Ah6A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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