SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21da358d3b50057e921af7513a30f0f3eb5a2dcbdf9d140ba7a0d3347e002f3b' 
  AND token = 'Xjet9lIOYyMw4D1qInEalONy7WIjq/FeryqtCmTQxbs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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