SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a65ffd5ef7190ed087280a7e3e155e9a1c7bd9ffe246dd80d1a65c33e9bc241c' 
  AND token = '5uhMQdTw/p2AVwqrgKXanK6FPqUka85xULaJli+ghVQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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