SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd2e8b960c59da7e0c553d803039a7b39bce7cff06dfc12b41d5fa91b83492b40' 
  AND token = 'iEl9rVs5+mNlAIuXnsoE6qeXEXpDGcHgjk/CeYrPK5c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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