SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a10a981f1a4e0c5703cd0b98f679d25a4862ba2a16d47331ff9b0cdac856ddc3' 
  AND token = 'sZ/ZRmqH0Adf7Y2LAW29UzvUX2rfqH/VubJVkVFKpxY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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