SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b897fc8092035e6d84746ef800502da03bb686f1c9e7b1364bca169b6b913541' 
  AND token = 'oMwqI1DJa5+ZRGcERdAEPpOA78kCtAJiifAY6IrggUI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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