SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '84f316c76da41ec9aff555d88559f800fbbf3aaae9a542741f7a5bb82d370dad' 
  AND token = 'MTi07SAVUKR3XvPdBOTAlIuhi1gxR5NbYGv5I+0URxM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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