SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '296f904f19ef11d958a36543598bac2983a85194f349d9a26c13a4595ccc3f10' 
  AND token = 'GV61mgAsPPDRBnUvakq/2Sw1xTN0PcLoTFh6ojcF5ao=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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