SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '733387bfd5bc2d6ceead97bc70fb820c102a98fe1fb1ff36f0616358de61e997' 
  AND token = 'FFGh+HRKXPyTmOwj9Mv9Vxuvp/yL76wDgAe9jGsXqTo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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