SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '96978e6a34fb303bf1e913aed9e7f92cc45dafe8de58863f3c5593d4a5374278' 
  AND token = 'PEwBIpKjOqp/xqmXXrYqNsU2Mi6/8YJ7PXePHksVSa4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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