SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b4c971eb044b127fafd3e63d322a83b3e5b6374ef295262409001e883895a64' 
  AND token = 'IIyyKwoxINX4f6p0STbyFXU9Esp/hDgxZ9LJ9dER3o8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}