SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '11b0f2ae7fbfdee0ef5100f545de8c8c386bd9aebdc387e1de0d1fe2e3c731af' 
  AND token = 'qxTt0ffzHtfw6lpJFxSZS1UFbPykUMeZ7ZMa/hYvQX0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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