SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '4cc9791ad24c6a3636bb944ec1e5c92a6c4a6a1e962f00af100983d9175688f6' 
  AND token = '9+0fpyeUeL2K/zJcM2gp9S/VNShkIpawuv8/YpBG7KU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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