SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '20fb7c7bcb45546dbc755330276baa0bd86494f86ee201f283fe243cecba984c' 
  AND token = 'BpPXAGhhIYPgsAWxNQw2xZc//60wtbCb69t2V88qcFg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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