SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f9b6491e1f5ed4ca5241684d8a7111a2f3f8db25762dacae7e03b508802419a8' 
  AND token = 'oZm2rumt5/npyfLHY+8hfwBPlLKHnMsVnpjUrYrDn4c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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