SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '291d75dec04e1a17af9284205cc3676780c24f30e5cef4d3783d007cdcf407c5' 
  AND token = '12gZ/XZ2XpO73tnVyOe37Ew5wj6/4oOzWMnEQDLIHwY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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