SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a264f42066e5187028cbd41d2e848a635c8e513bb11b68ede7be7ffa4e249bac' 
  AND token = '2QJK91/l8d5pVUPGDPNs2yDcgzspuVHNgf8Z6dCMrak=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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