SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2316d868ec6605f3bc3e55ddd97e847fea4735c3f1cbe4a35a46ef9dc0d646b' 
  AND token = 'el2mLPRbl+MFYqMKrHPOX7iYqAO7c2YLytCdClU0MJ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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