SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6580be4b341df4ed143e7bdf15438be62f73b23b19aa6b112c7f07fe722eaa51' 
  AND token = 'r3D3WDuKRd1ycRUChRqmMPy714fD4DeW24w+4E1ZlME=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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