SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '740cabb792238d6a4e849aa0e87b69ecbdc0be8fe1b0557124ae28983248a6dc' 
  AND token = 'iLjg4+Q187Q1wMtOCM5CHOWS5uDMv1PmEMlZpcxZlRk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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