SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f4a0c313d8b0d0792182c745cfdd0641de85ea44344d951f0cd9df2a348fe8e5' 
  AND token = 'SDfLrekditcqC+MRYWIopln58DMjdCKSvGIvuhJdMgM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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