SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '860f0cf43b2b56dfd6377d18048b7740e9c36461a3b246d1af0245d789d07f6b' 
  AND token = 'NWHjOvtfPqy9OsPDXk3qRROjJwMBPBMcfCRRYLiP07c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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