SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f312d52cfa4691254867479b832d416bc0058c65bd72b22e70305da188f309a4' 
  AND token = 'vI4EkGCQe6DVTfFZehl/EtBpxlHJmHZcS0l68KXFqLE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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