SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd16d2d78115af618b8f99d91dd996554c2a30512a64cb5d2b70a71de97024419' 
  AND token = 'heCcayeCrNbOMWmoAddP63nMQNQ+ZXOr55Oxn2Lwu4w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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