SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd631e74612a6af1b3e79523395abb8f10c76aaae84650b29128772e5a9d27f96' 
  AND token = 'QgqK7laE+kJG9Am2raqfgCBUOJKwaai/dvZcPMdvwt0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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